二分查找算法详解-优快云博客

本文链接：https://blog.youkuaiyun.com/Sanguinity/article/details/101164912

本文深入探讨了二分查找算法的两种实现方式：非递归和递归。通过具体的Java代码示例，详细解释了每种方法的工作原理，并提供了运行示例以验证其正确性。适合初学者和进阶学习者理解并掌握二分查找算法。

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public class binarysearch {
    /**
     * 二分查找---非递归实现
     *
     * @param arr
     * @param val
     * @return
     */
    private static int binarySearch(int[] arr, int val) {
        int left = 0;
        int right = arr.length - 1;
        while (left <= right) {
            int mid = (left + right) / 2;
            if (arr[mid] == val) {
                return mid;
            } else if (arr[mid] > val) {
                right = mid - 1;
            } else {
                left = mid + 1;
            }
        }
        return -1;
    }

    /**
     * 二分查找---递归实现
     *
     * @param arr
     * @param val
     * @return
     */
    private static int RecursivebinarySearch(int[] arr, int val) {
        return RecursivebinarySearch(arr, 0, arr.length - 1, val);
    }

    private static int RecursivebinarySearch(int[] arr, int left, int right, int val) {
        //递归首先判断结束条件
        if (left > right) {
            return -1;
        }
        int mid = (left + right) / 2;
        if (arr[mid] == val) {
            return mid;
        } else if (arr[mid] > val) {
            return RecursivebinarySearch(arr, left, mid - 1, val);
        } else {
            return RecursivebinarySearch(arr, mid + 1, right, val);
        }
    }

    public static void main(String[] args) {
        int[] arr = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        System.out.println(binarySearch(arr, 5));
        System.out.println(binarySearch(arr, 12));
        System.out.println(binarySearch(arr, 1));
        System.out.println(binarySearch(arr, 10));
        System.out.println();
        System.out.println(RecursivebinarySearch(arr, 5));
        System.out.println(RecursivebinarySearch(arr, 12));
        System.out.println(RecursivebinarySearch(arr, 1));
        System.out.println(RecursivebinarySearch(arr, 10));
    }
}